Machine for making hollow plastic articles



Nov. 6., 1951 Q W, DE BELL 2,573,693

MACHINE FOR MAKING HOLLOW PLASTIC ARTICLES Filed NOV. 14, 1947 A 2 SHEETS-SHEET l Nov. 6, 1951 Filed NOV. 14, 1947 G. w. DE BPELL MACHINE FOR MAKING HoLLow PLASTIC ARTICLES 2 SHEETS-SHEET 2 Patented Nov. 6, 1951 For.; MAKING-119mm @Alsina @RTICLYlJzsx GMS@ W De Bell Stmfd C9119'- @211mm liozembglz 11,1941, serial; 1:1947@ gllaimsQ (01.18726) mammie; an@ wm; the hating.

moved frbm the oscillating frame I6 may be assembled by any suitable means, but they are also preferably welded together, as indicated at 23 and 24.

Suitably mounted on the upright I2 by any suitable means, such as an intermediate block 25, is an upright circular disc 26 which may be secured to the block by welding, .as shown at 21, and the bearing I4 for the oscillating frame I6 may be mounted at the center of this disc. The frame I6 carries a rotatable shaft 28 mounted to rotate in suitable bearings 29 in the cross members I9 and 28, and at its lower end is a driving pulley 38, preferably a V-pulley, operated by a V-belt 3I from a driving pulley 32 on a drive shaft 33 mounted in a suitable bearing 34 in an extension of the member I9, and a second bearing 35 mounted in an extension block 36 to which the upper end of the side member I1 is connected.

The pulley 30 preferably 'drives shaft 28 through a friction clutch or drive 30a to permit turning ofmold 64 independently of the shaft to the position most convenient for opening it. Mounted on this shaft is a friction drive pulley 31 provided with a frictional driving ring 38, such, for example, as a suitable fiber or rubber material running on the surface of the disc 26. The pulley 31 is adjustable longitudinally on the shaft 33 to vary its distance from block 36 and shaft 39 and thus vary the speed at which shaft 33 and thus shaft 28 and the mold 64 are driven. Pulley 31 may be splined to shaft 33 by a key or set screw 31a running in a longitudinal groove or key way 33a in theshaft, and secured in adjusted position by set screw 31h. The block 35 is mounted on a shaft 39 in the bearing I4, and the shaft is extended from plate 26 a suicient distance for a coll spring 40 to embrace this shaft and at its outer end bearing against a suitable washer 4I on this shaft and at its inner end against a suitable block 42 at the outer side of the plate 26 and splined to the shaft, as indicated at 43, to turn with the shaft but permit the shaft to have longitudinal movement with respect to the block. With this arrangement the spring 48 tends to shift the shaft and the parts carried thereby to the left as viewed in Fig. 1, and thus always maintain the drive pulley 31 in proper frictional contact with the surface of the plate 26 for effective driving operation. The pressure of the spring and therefore the'pressure of the pulley against the plate may be varied to suit conditions by means of the adjusting nut 4I a.

The other upright member- I8 is supported by a similar block 44 at its upper end secured to a hollow shaft 45 running in the bearing I5 and adapted for longitudinal movement in this bearng under action of the spring 48. Mounted on this side member I8 by means of a suitable stud 46 secured in this member and by means of a suitable bearing 41 is an arm 48 provided with a longitudinal channel 48 to adjustably receive a link 50 secured in the channel for longitudinal adjustable movement by any suitable means, such, for example, as a transverse clamping strap 5I. This link 50 is connected at its opposite end to a crank pin 52 by any suitable bearing 53, and which crank pin is adjustable longitudinally in a crank 54 secured to a crank shaft 55 mounted in a suitable bearing 56 in the side member I3. On this shaft 55 is a pulley 51, preferably a V-pulley operated by any suitable means, such as a V-belt 58 from the drive pulley 59of a suitable electric .motor 60, the pulley 58 being driven from the ,motor by any suitable reducing gear train drive assembly 6I, so that the shaft 55 is driven at 4 considerably less speed than the speed of the motor. The crank pin 52 may be mounted by any suitable means for adjustment in the crank 54, but a satisfactory arrangement is to provide the crank with a longitudinal T-shaped slot 62 and mount the pin 52 in a suitably shaped block 63 slidable in this slot. Itwill be understood that by adjusting the link ornbar' longitudinally in the member 48, the block 63 is also shifted in the crank 54, and the angular speed of oscillation of the frame I6, and also the amount or amplitude p of this oscillation, may be varied as desired.

I6 and the oscillatory or rocking movement of this frame, the mold will be given a combined rotary and oscillatory movement about different axes at right angles to each other. In the present illustration the mold 64 is the mold for moldingV a generally cone-shaped or tapered mute for a trumpet, shown in section at 65, but it is to be unl-Y derstood that a mold for this particular article is shown merely by way of example to illustrate the operation of this machine and the method of molding, and that molds for differently shaped or different types of articles may be used as desired. This mold for molding this particular article is made in two sections 66 and 61 hinged together at 68 on one side and connected at the opposite side by a suitable releasable catch69. The dividing line 10 between the mold sections is on the largest diameter of the article to be molded, so that when the mold is opened by re' leasing the catch 69 and swinging the upper section about the hinge 68, the two sections may readily separate to release the molded article 65, and after the mold is opened the article may be readily removed from the mold. The pulley 30 preferably drives shaft 28 through a friction clutch or drive 30a to permit turning of the mold to a position most convenient for opening this mold. This mold is mounted on the shaft 28 above the transverse support 20 where it is readily accessible and free from interference with the operative elements of the machine. It is secured to the shaft by any suitable means, such, for example, as mounting it on the plate 1I secured to a sleeve 12 mounted on the shaft and secured thereto by any suitable means, such for example, as the set screws 13,. the axis of the mold cavity being in alignment with the axis of the shaft 28. This particular article is circular in cross section at right angles to its axis, but the device and method is not limited to this type of article, as a large number of differently shaped articles may be molded by this machine and method. n

Where thermosetting plastic materials are used fory molding the article, heating means is provided for maintaining the temperature of the mold at the proper temperature for curing and setting this material. It is, however, to be understood the device is not limited to use for molding thermosetting materials, but may be used'for molding other plastics or moldable materials, including metals. Thus, in the device illustrated, the lower or head section of the mold is heated to the proper temperature by an electric resistance heating unit 14 mounted in suitable insulating material 15 and separated from the mounting 1I by a layer of heat insulating material 16. Also the body of the upper section 66 of the mold is surrounded by a suitable electric resistance heating unit 11 in any suitable -insulating material I8 and surrounded by heat inattrarre jrssspeiscesef tirs ;current for the heating cous gr unitsii and 11 s* Supplied by means ofalead cable 85 adapted to beA connected by any Vsuitable plug connection 8B to an electrical outlet of anelec'tric systeii'i; and passing tlirough the hllovv shaft 45 a pair of brushes 87 mounted in a block 8B of insuietingmateriai mounted on the supportati and-provided with radial sockets in `vv'hich these briishes are mounted and which theyr are.

connected to the leads of the cable 85, as' indi-- cated at 89. These brushes contact laterally spaced and insulated slip rings 953' and Si of suit-y able electrical conducting metal and mounted in a .suitable insulating support mounted on the lsleeve l2 so as to rotate with the shaft 28 and therefore with theV mold. This support for the .slip rings comprises an intermediate disc 92 of suitable insulating material, such as compressed fiber provided with a peripheral rib 93 on the opposite sides of which the slip rings are located. The rings are held in this position by the outer discs or plates @il and 95 of insulating material on Opposite sides of the center ring 92 and secured to it and to each other by any suitable means. Suitable lead Wire connections 96 and Sl areV connected with the respective slip rings and connected to the oppositeends ofthe heating elements lll and 'il through the automatic con-'- Vtro l 80. s.

The thermosetting, thermoplastic or other plastic or molding material from which the article is to be molded Ais placed -i-n the cavity of the mold after the mold is closed through an opening 9.8 .in -theouter or top end of the mold,

and after the material is placed in the mold this cavity is closed by means of a suitable closure plug 93 operated Nby asuitable handle mi), the plug l'being provided vv'ith Va small lvent mi to permit escape of gases from the mold formed incident to the molding operation, and prevent these gases building upl pressure Within the mold This vent, however, is not always necessary. Also, although a single cavity mold is shown vit yvill 'be understood a multiple cavity -mold may f .f

`be used. The plug is removably 'held '.in position Lby any suitable means. In the present construc- 'tion it isprovided with a transverse bar or plate Hl-2 adapted by turning movement of `the plug to slide -at its opposite ends in notches |83 -formeel in lugs E06 on the top ofthe mold v with the :notches We opening in opposite directions, so "that by turning the handle Il!!! and the bar '|102 to the left, as shown in Fig. 3, to bring the'handle to the dotted line position ia, theenlsiof *the "bar "IM are removed from the notches IED-3, rel'easing the plug 99 so that `it may 'be 'removed 'if-rdm the mold and may 'be reinserte'd `to lclose 'the opening 9B by reverse operation. Vflftr-:rfthe lplu'g "is lreriiove'd, the proper measured amount fof Imaterial may lbe ldep'osited f in the vinold cavity bya suitableform of pressuregun ='(not shown) having a nozzle insert'abl'e through :open-ing 29B alid aiplunger in the cylindert'o force the@ 'a'- Cterial into 'the cavity jin the mold.' Byf-meaiis a gn the erase amen or mtriai fer fnldinfgacl dividuall art measured /I'id deposited in? the moldc'avityL This operation', however; is performed preferably when the'rn'oldy isE in -an inclined position, substantially as shownii'r Fig". 2, friiiir'gA a puddle' indicated at H15' in the lovv'er portieriof the mold cavity. The plug 99 may be omitted and the charge ofA material placed irfr the mold cavity While the mold is open befre dlcs'ir'igV it. lf a closed lower end is to be formed n theV article, this puddle must be large enough so to extend'over the center peint [06 ol" o'f the article being molded. Then after closing thelli'ng opening 93, asV the machine dperates through rotation of the crank 54 by the rii''itor; its movement being inthe direction of the arrow" 191, Fig. 2; the frame I6 will be oscillated to the right,- r clockwise as viewed in Fig. 2, about thealignedaxes of the shafts 39 and 4-5, this operation gradually tipping the upper or free end of the mold downwardly to any position desired,- depending on the shape of the article being molded. In the present example of molding the conically shaped mute, it is tipped to substan: tiallyv the position of Fig. '7, so that the pool or puddle 165 of the liquid thermosetting .material hasV a chance to flow over all of the interior sur- Afaces of the mold cavity Ii El for the entire length thereof. During this oscillating or tipp-ing movement of the frame i6, the friction drive pulley 31 running over the surface of the plate 23 is rotated and through the pulley drive 32, 3l, 33 Will rotate the shaft 28 and therefore rotate the mold aboutits longitudinal axis. This, therefore, car` ries the puddle i515 of molding material over the entire inner surface of the mold, `causing it to cover this surface to the desired thickness for the thickness of the Ivva'll of the article 65 being molded, and which material is cured and set on these'wal'ls ofthe cavity by the heat from the heating units 'M and Tl in the mold.

ItWi'lL therefore, be understood that vduring the molding operation the plastic molding material isevenly distributed over the surfaces of the mold cavity by the combined oscillating or tipping action of the mold With the frame I6 and the rotary motion of 'the mold about its longitudinal axis 'caused by rotation of the shaft 2.8, Quring these .movements of the .mold the puddle 1'0'5 of thelicfuid plastic material remains in the lovvest part 'of the mold cavity and spreads itself evenly. over the mold surfaces by this comibi'ried oscillating and rotating motion. The mold inayrotate in one direction only if desired, b'ut in mfaki'ng a complete article best results are secured kby rocking it over and back. The operation is `'about Ativo intersecting axes, and it could be operated by 'continuous rotation in ,one direc- 'tion or oscillation 'about these axes. A driving arrangement 'for `continuous operation 'in one direction is shown diagrammatically in Fig. 8. In this arrangement a pulley Ia is connected 'toblock M -br :directly to frame i6 carrying -the I-mold. '6% and its operating shaft 28, and con- ;iictedby 'la -suitable driving belt 59a with the vdrivingj'pulley A#55). In this case electric current frvtouli'i 'tbe `1supplied to the heating lunits `vfor the mold `by "aslip ringand :brush arrangement l88 Lthe same las fthatsliown in Fig. 1. If the mold Vrotated in one direction only, the operation rfi-rust be fast Lellbllgh 'to `-tuI-n liti-Substantially upside dott-n, or atleast to its extreme position, `las EFgf. 7,' and -back again ibefore the Vmaterial is entirely Eset. That ikis, lthe puddle must -go T'the before the material at the starting nd is Sufj ficiently cured to prevent a permanent bond with the next outer layer. Also, the mold must make a complete turn before the puddle leaves any longitudinal portion of the mold cavity in order to cover the complete peripheral surface of the mold cavity. It will also be seen that one rotation, that is, the rotation about the longitudinal axis, is suilciently faster than the other or the oscillating movement so that the puddle makes a continuous layer or wall by an overlapping spiral, and this is repeated by the reverse oscillating movement before the material at the lower end or original puddlefhardens suiiiciently so as not to bond with the next layer. On the other hand, both rotations must be sufficiently slow not to develop a centrifugal force greater than the pull of gravity, so that the puddle will remain at the lower side of the cavity and follow around and cover all the surfaces of the mold cavity and not be collected at the largest diameter, as it would in the case of centrifugal action. In molding an article, such, for example, as the article 65 in the present example, in which an opening |08 is desired in one end, the plug 99 is made long enough to extend into the mold beyond the thickness of the wall of the article, as shown in Fig. l, but if a closed end is desired with no opening, then the closure plug 99 would be made only long enough to come at its inner end to a position flush with the end wall |09, and the plug in this case would not be vented. This same procedure would be used in molding such articles as a hollow ball, for example, with continuous walls and no opening. It is not necessary that the axis of the mold be on the axis of the shaft 28, as the necessary rotation can be secured by planetary movement of the mold about the axis of the shaft.

Various plastic material can be molded in this machine. The articles in the example shown have been molded by a thermosetting material comprising a polyester resin with suitable accelerators and also llers, such, for example, yas fiber glass, asbestos, or other suitable fibrous material to increase the strength f the molded article and also to reduce the amount of the more expensive plastic or resinous material and thus reduce the cost of the article, but the amount of filler should not be suilicient to interfere with the proper molding action. The thermosetting action is a polymerization. A mixture which has been used comprises a mixture of two monomers which are changed to polymers with exothermic reaction. A material which has been used and found very satisfactory is a mixture of polyester resinous materials; for example, about 50% each of resins sold on the market as Plaskon S60-1l and Plaskon 920-11, the first being quite flexible and the second less flexible, the mixture of the two giving a resin of the proper strength and flexibility.

In other words, the material is a thermosetting contact pressure plastic resin, that is a polyester contact pressure resin, say of 100 parts, with an accelerator for the resin as required by the manufacturer of from 2 to 4%, depending on the time desired for the setting. These are usually oxidizing agents, such, for example, as benzoyl peroxide. A contact pressure setting resin isrone that is capable of curing satisfactorily at atmosfpheric pressure by the application of heat.k With 100 parts of resin, the specified amount of catalyst and oxidizer should be used, as specified by the manufacturer. Color pigments may also be used.

One and one-half per cent has been used for white and one-half per cent for black. Filler may be glass liber flock, asbestos, or other suitable bers. The ller should be an amount which will not prevent the puddle of the material properly flowing around the surface of the mold cavity. In other words, as much flock or filler may be used as can be added without increasing the viscosity at molding temperature to the point where the puddle will not remain at the bottom of the mold cavity during rotation of the mold. The filler is not essential, but has been used in these articles to increase the mechanical strength of the particular resin used. Also a coating may be used to prevent bubbling at the surface, so as to produce a smooth continuous surface. A small amount of the same resin could be used with about 50% of accelerator with no ller in this coating. Also, an antifoam or wetting agent might be used to lower viscosity and reduce foaming and increase the wetting properties. A parting agent or mold lubricant could also be used applied to the surface of the mold cavity before placing the molding material in it to insure that the plastic molding material will not stick to the surface of the mold. A so-called mold release fluid is available on the market under the name Vejin, or a silicon base product may be used for the same purpose.

It will be seen from the above by this device and method articles of various shapes may be molded as a unitary structure in one piece from thermosetting or other types of plastics. It is not limited to use with thermosetting plastics, but may be used with cold setting or other types of plastics. As the article is molded in one unitary piece there are no separate pieces to be assembled and there are no joints between the sections to become separated or loosened. Also the article can be completed in a single molding operation, eliminating assembling costs. Articles may be molded either with an opening to the interior of the hollow article, as in a bottle, for example, or the hollow article can be molded in one piece without any opening, as a hollow ball, for example, providing such articles without a seam or joint of any kind.

Having thus set forth the nature of my invention, I claim:

l. A machine for molding hollow articles comprising a base, a frame mounted on the base for turning movement in an upright plane about a stationary horizontal axis, a mold mounted on the frame, cooperating means on the base and frame for rotating the mold about an axis running through the mold at substantially right angles to the axis of movement of the frame and operated by turning movement of the frame, and drive means connected to the frame to positively drive the frame a partial revolution rst in one direction and then in the other to rotate the mold first in one direction and then in the other during the molding operation.

2. A machine for molding hollow articles comprising a shaft, a mold mounted on the shaft with the axis of the shaft running through the mold, driving means to swing the shaft first in one direction a partial revolution in the plane of the shaft and then a partial revolution in the opposite direction, and a driving connection between the rst driving means and the shaft operable by swinging movements of the shaft to rotate the shaft and mold about their axes as the shaft is so swung back and forth to rotate i the mold first in one direction and then in the other during swinging movement of the shaft.

3. A machine for molding hollow articles comprising a mold having a cavity of the size and shape of the article to be molded, means mounting the mold for rotation about an axis running through the mold, means mounting the mold for turning movement about a stationary axis at substantially right angles to the rst axis by movement of the first axis in the plane of this axis, driving means for turning the mold first at least a partial rotation in one direction about the stationary axis and then at least a partial rotation about this axis in the other direction, and a driving connection from the driving means to the mold operable by movement of the mold about the stationary axis to turn the mold about the first axis nrst in one direction and then the other as the mold is swung about the stationary axis.

4. A machine for molding hollow articles comprising a mold having a cavity of the size and shape of the article to be molded, a base support, a frame mounted in the support to turn about a horizontal axis, a shaft mounted in the frame to rotate about an axis at substantially right angles to the rst axis, means mounting the mold on the shaft with the axis of the shaft running through the mold, driving means for oscillating the frame to swing it about the horizontal axis rst in one direction a partial revolution and then in the other direction a partial revolution, and a driving connection from the base to the shaft operable by swinging movement of the frame to rotate the shaft and mold rst in one direction and then in the other about the axis of the shaft.

5. A machine for molding hollow articles comprising a mold having a cavity of the size and shape of the article to be molded, a support, a frame, means mounting the frame in the support to turn about a fixed axis, a shaft, means mounting the shaft in the frame to turn about an axis at substantially right angles to the first axis, means mounting the mold on the shaft with the axis of the shaft ruiming through the mold, means for oscillating the frame about the first axis to turn it first in one direction and then the other, and means operated by turning movements of the frame to turn the shaft and mold rst in one direction and then the other during movements of the frame.

6. A machine for molding hollow articles comprising a mold having a cavity of the size and shape of the article to be molded, a support, a frame, means mounting the frame to turn about a substantially horizontal axis, a shaft mounted in the frame to turn about an axis at substantially right angles to the first axis, means mounting the mold on the shaft with the axis of the shaft extending through the mold, an upright plate, a friction wheel carried by the frame and running on the plate, means for turning the frame about the first axis with the shaft axis moving in the plane of this axis comprising a rotatable crank mounted in the support, an adjustable link connecting the crank with the frame to oscillate the frame about the rst axis, and a driving connection from the wheel to the shaft; to operate the shaft by turning movements of the frame.

7. A machine for molding hollow articles comprising a mold having a cavity of the size and shape of the article to be molded, a support, a frame, means mounting the frame in the support to turn about a horizontal axis, a shaft mounted in the frame to rotate about an axis at substantially right angles to the first axis, means mounting the mold on the shaft with the axis of the shaft extending through the mold, an upright plate mounted in the support, a friction wheel mounted in the frame and running on said plate during movements of the frame, a crank mounted in the support and connected to the frame for operating it, power means for operating the crank, and a driving connection from the friction wheel to the shaft for operating the shaft during movement of the frame and inciudinCr means whereby the position of the ywheel may be adjusted radially of the first axis to Vary the speed of operation of the shaft.

8. A machine for molding hollow articles com: prising a mold having a cavity of the size and shape of the article to be molded, said mold being provided with an opening leading to the cavity for insertion of a measured charge of molding material to form a puddle at the lower part of the mold cavity, a plug for closing said opening and provided with a vent passage, means for detaohably securing the plug in the opening, said mold comprising separable sections, heating means for the mold sections, means for simultaneously turning the moid about different axes at substantially right, angles to each other to flow the puddle over the surface of the cavity, one of said axes extending through the mold cavity and movable about the other axis in the plane of the movable axis, said driving means for the mold including a support, a frame mounted for turning movements in the support, a rotatable crank mounted in the support, a driving link connecting the crank and frame to oscillate the frame by 'turning movements of the crank, a driving connection from the support to the shaft operating by swinging movements of the frame to turn the shaft about its axis as the frame oscillates, and means for supplying heating medium to the heating means during said movements of the mold.

9. A machine for molding a hollow article comprising a mold provided with an oblong cavity of the size and shape of the article to be molded,

said mold being provided with a charging opening in one end for insertion of a charge of molding material to form a puddle in the lower part of the mold, a plug for closing said opening, means for detachably securing `the plug in the opening, means mounting the mold to rotate about the longitudinal axis of the cavity, means mounting the mold to turn about an axis at substantially right angles to the first axis by movement of the first axis in the plane of this axis, and means for simultaneously rotating and turning the mold about said axes comprising means for oscillating the mold in opposite directions about the second axis, and means operable by oscillating movement of the mold to rotate the mold about, the first axis in opposite directions as the mold oscillates, to flow the puddle over the surface of the cavity during setting of the material.

GEORGE W. DE BELL.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date '803,799 Voelke Nov. 7, 1905 1,784,686 Fauerbach Dec. 9, 1930 1,995,977 Gonda Mar. 26, 1935 2,222,266 Rubissow Nov. 19, 1940 2,466,277 Rubissow Apr. 5, 1949 

